it is true. land heats and cools faster than water surface. land heats faster than water due to the fact that land is dull in color and therefore absorbs more heat. on the other hand water surface is brighter and reflects more of the heat from the sun. remember dark colors absorb more heat than bright colors and bright colors reflect more heat that dark colors. on the other hand, land cools faster than water because heat energy is stored in shallow layer close to the surface of the land and as a result can be radiated much more faster. again the amount of heat energy stored in water column is much more than that stored in land.